[PATCH v4 3/3] coresight: dummy: Add static trace id support for dummy source

[Mao Jinlong]

Some dummy source has static trace id configured in HW and it cannot
be changed via software programming. Configure the trace id in device
tree and reserve the id when device probe.

Signed-off-by: Mao Jinlong <quic_jinlmao at quicinc.com>
---
 .../sysfs-bus-coresight-devices-dummy-source  | 15 +++++
 drivers/hwtracing/coresight/coresight-dummy.c | 59 +++++++++++++++++--
 2 files changed, 70 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-coresight-devices-dummy-source

diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-dummy-source b/Documentation/ABI/testing/sysfs-bus-coresight-devices-dummy-source
new file mode 100644
index 000000000000..db770bc972d9
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-dummy-source
@@ -0,0 +1,15 @@
+What:		/sys/bus/coresight/devices/dummy_source<N>/enable_source
+Date:		July 2024
+KernelVersion:	6.9
+Contact:	Mao Jinlong <quic_jinlmao at quicinc.com>
+Description:	(RW) Enable/disable tracing of dummy source. A sink should be activated
+		before enabling the source. The path of coresight components linking
+		the source to the sink is configured and managed automatically by the
+		coresight framework.
+
+What:		/sys/bus/coresight/devices/dummy_source<N>/traceid
+Date:		July 2024
+KernelVersion:	6.9
+Contact:	Mao Jinlong <quic_jinlmao at quicinc.com>
+Description:	(R) Show the trace ID that will appear in the trace stream
+		coming from this trace entity.
diff --git a/drivers/hwtracing/coresight/coresight-dummy.c b/drivers/hwtracing/coresight/coresight-dummy.c
index ac70c0b491be..3bf5437cbfb1 100644
--- a/drivers/hwtracing/coresight/coresight-dummy.c
+++ b/drivers/hwtracing/coresight/coresight-dummy.c
@@ -11,10 +11,12 @@
 #include <linux/pm_runtime.h>
 
 #include "coresight-priv.h"
+#include "coresight-trace-id.h"
 
 struct dummy_drvdata {
 	struct device			*dev;
 	struct coresight_device		*csdev;
+	u8				traceid;
 };
 
 DEFINE_CORESIGHT_DEVLIST(source_devs, "dummy_source");
@@ -67,6 +69,32 @@ static const struct coresight_ops dummy_sink_cs_ops = {
 	.sink_ops = &dummy_sink_ops,
 };
 
+/* User can get the trace id of dummy source from this node. */
+static ssize_t traceid_show(struct device *dev,
+			    struct device_attribute *attr, char *buf)
+{
+	unsigned long val;
+	struct dummy_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+	val = drvdata->traceid;
+	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+static DEVICE_ATTR_RO(traceid);
+
+static struct attribute *coresight_dummy_attrs[] = {
+	&dev_attr_traceid.attr,
+	NULL,
+};
+
+static const struct attribute_group coresight_dummy_group = {
+	.attrs = coresight_dummy_attrs,
+};
+
+static const struct attribute_group *coresight_dummy_groups[] = {
+	&coresight_dummy_group,
+	NULL,
+};
+
 static int dummy_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -74,6 +102,11 @@ static int dummy_probe(struct platform_device *pdev)
 	struct coresight_platform_data *pdata;
 	struct dummy_drvdata *drvdata;
 	struct coresight_desc desc = { 0 };
+	int ret, trace_id;
+
+	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
 
 	if (of_device_is_compatible(node, "arm,coresight-dummy-source")) {
 
@@ -85,6 +118,25 @@ static int dummy_probe(struct platform_device *pdev)
 		desc.subtype.source_subtype =
 					CORESIGHT_DEV_SUBTYPE_SOURCE_OTHERS;
 		desc.ops = &dummy_source_cs_ops;
+		desc.groups = coresight_dummy_groups;
+
+		ret = coresight_get_static_trace_id(dev, &trace_id);
+		if (!ret) {
+			/* Get the static id if id is set in device tree. */
+			ret = coresight_trace_id_get_static_system_id(trace_id);
+			if (ret < 0)
+				return ret;
+
+		} else {
+			/* Get next available id if id is not set in device tree. */
+			trace_id = coresight_trace_id_get_system_id();
+			if (trace_id < 0) {
+				ret = trace_id;
+				return ret;
+			}
+		}
+		drvdata->traceid = (u8)trace_id;
+
 	} else if (of_device_is_compatible(node, "arm,coresight-dummy-sink")) {
 		desc.name = coresight_alloc_device_name(&sink_devs, dev);
 		if (!desc.name)
@@ -103,10 +155,6 @@ static int dummy_probe(struct platform_device *pdev)
 		return PTR_ERR(pdata);
 	pdev->dev.platform_data = pdata;
 
-	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
-	if (!drvdata)
-		return -ENOMEM;
-
 	drvdata->dev = &pdev->dev;
 	platform_set_drvdata(pdev, drvdata);
 
@@ -126,7 +174,10 @@ static void dummy_remove(struct platform_device *pdev)
 {
 	struct dummy_drvdata *drvdata = platform_get_drvdata(pdev);
 	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node;
 
+	if (of_device_is_compatible(node, "arm,coresight-dummy-source"))
+		coresight_trace_id_put_system_id(drvdata->traceid);
 	pm_runtime_disable(dev);
 	coresight_unregister(drvdata->csdev);
 }
-- 
2.41.0